Current responsive switch



Aug. 19, 1947. J. w. MccLAlN CURRENT RESPONSIVE 'swn'ca Filed Jan. 3,1945 il. lllllllllli 'Humm J Inventor. j JosephW.McCla`ir1, i El Histtcney.

Patented Aug. 19,l 1947 2,426,038 CURRENT RESPONSIVE SWITCH Joseph W.McClain,

New York Schenectady, N. Y., assignor to General Electric Company,

a corporation of Application January 3, 1945, Serial No. 571,140

(Cl. 20G- 116) 8 Claims.

My invention relates to current responsive switches, more particularlyto current responsive switches for opening the circuit of a load device,such as an electric motor, in the event of an excessive current in thecircuit, and has for its object a reliable and inexpensive switchproviding for manual opening of the circuit and for spring opening inresponse to an excessive current in either of two legs of the circuit.-

In carrying out my invention in one form, I provide a shaft which isconnected to a carrier member rotatably mounted on the shaft andnormally held in a predetermined position by a latch so that th'e shaftmay be moved manually between open and closed circuit positions. Anovercenter snap spring mechanism is attached to the end of the shaft togive proper positioning of the shaft when operated. I also providecurrent responsive means in each of two legs of the circuit to beprotected for separately effecting the operation of the latch to releasethe carrier member, whereupon the` carrier` member and shaft are movedtogether by spring biasing means to open the circuit.

For a more complete understanding of my invention, reference should behad to the accompanying drawing, Fig. l of which is a front elevationview of a current responsive switch embodying my invention and showingthe parts in their switch closed positions; Fig. 2 is a fragmentary viewsimilar to Fig. 1 showing the parts in their manually open position;Fig. 3 is a view similar to Fig. 2 showing the parts in their currentresponsive open position; while Fig. 4 is an explodedl view inperspective of the device shown in Figs. l-3 inclusive.

Referring to the drawing, in one form of my invention I provide anoperating shaft I (Fig. 4) having secured to it a cam 2 provided with anoperating portion extending through an aperture 3 in a slider switchoperating member 4 made of electrically insulating material. Mounted onthe slider member 4 are three bridging contact members 5, 6 and 1 biasedupward, as seen in the drawing, by suitable springs. By means oi asuitable handle 8, the shaft I can be turned to move the slider member4. As shown, the slider member is in its raised vposition with thebridging contacts in engagement with three pairs of stationary contacts9, I0 and Il. By turning the handle 8 clockwise substantially 90degrees, the plate 4 is moved downwardly to the dotted line open circuitposition in which the bridging contacts are separated from the pairs ofstationary contacts.

A snap movement is imparted to the shaft I by means of an overcenterhelical compression spring I2 surrounding a link I3 connected through apivot has a cylindrical portion which extends tightly through atransverse aperture in the shaft I so as to secure the arm I5 rigidly tothe shaft, while the lower end of the link I3 cooperates 'with a carriermember I6 which is rotatably mounted on the shaftvi. The end of the armI5 projecting from the opposite end of the shaft engages a pin I5' (Fig.4) secured to the carrier member when the switch is closed thereby tolimitthe rotation of the shaft I in the switch closed direction, theengaging parts constituting stop means.

By means of a helical spring I1, the carrier member is biased in aclockwise direction about the axis of the shaft I with respect to astationary support I8, the carrier member being normally held againstthe bias of the spring I1 in the position shown in Fig. 4 by a latch armII). On the lower end of the carrier member is a link 20 which issubstantially U arms embracing two projections 2i and 22 on the lowerend of the carrier member. On the upper ends of the arms of the member20 are inwardly extending projections which engage the upper edges ofthe projections 2l and 22 and form pivots whereby the member im ispivoted on the carrier member.y Each of the projections M and 22 isprovided with spaced projections 23 and 24 on its lower end which formstops and between which the member 20 is free to move pivotally when theshaft is turned by the handle 8 thereby to reverse the bias of theovercenter spring I3 and-give the shaft a snap movement.'

As seen in Fig, 2, the link Il". is provided with two divergingprojections 25 andv 2B which embrace the member 2li, the overcenterspring I2 being conical in shape so as to fit loosely over the twoprojections. It will be observed that when the handle is turnedclockwise from the position shown in Fig. 4, the projections 25 and 26are moved downward on opposite sides of the member 20, whereby theovercenter spring is compressed. Then when the pivot I4 moves to theleft hand side of the' pivot axis of the upper ends of the member 20,the spring gives the member 20 a counterclockwise bias whereby themember 20 snaps to the position shown in Fig. 2 carrying the lower endof the snap spring toward the right hand to a position to the right of aline extending through the pivot I4 and the axis of the shaft I. Thissuddenly causes the spring I2 to apply a clockwise bias to the shaftwhereby I4 with an arm I5. The arm I5 -shaped and with its a stationaryprojection 26a.

its movement is completed with et smtp action and the switch opened.Counterclcckwise movereverse movement of the parts, the carrier memberat iirst being held against counterclockwise rotation by engagement ofthe projection 22 with In the closed position the end oi link I5 engagesthe pin I5 to limit the rotation of the shaft in the closed circuitdirection.

For effecting movement of the latch I9 upward about its stationary pivot21 thereby to release the are connected electrically in two of the threecircuits controlled by the pairs of switch contacts 9, I9 and 'II, suchas the supply lines or conductors for a three phase motor. Morespecifically, the thermcstatic tube 29 has its upper end secured to asupport 39' and its lower end provided with a slot 3| through whichextends an arm 32 mounted on a pivot 33 and biased downward i about thepivot by a spring 34 against the lower wall o! the slot 3|. A suitableresistance type electric heater 35 is inserted in the tube 29 and hasits terminals at its upper end connected in circuit with one of thepairs of stationary contacts soy that the thermostatic tube 29 is heatedin accordance with the current in the circuit o! that pair of contacts.

When the tube 29 is heated, it expands, and since its upper end issecured, its lower end moves downward, thus permitting the spring 34 tomove the arm 32 downward until finally in response to a predeterminedexcessive current in the heater 35, the arm 32 disengages the lower endof a latch 39 mounted on a pivot 31 on the lower end of a release arm39. When released, the arm 39 is moved by a spring 39 clockwise aboutits pivot 49 whereby a transversely extending arm 4I carried by it ismoved upward, as seen in Fig, 3, to release the lower end of the latchlink 42 whose upper end is mounted on a pivot 43 secured to an arm 44.'I'he arm 44 is in turn secured to the latch I9. Therefore, when the arm4I moves upward, the lower end of the latch link 42 is free to move tothe right hand and upward, the arm 44 being biased counterclockwise, asseen in Fig. 4, by a spring 45.

When the carrier member I9 is thus released by movement of the latch I9,the shaft I is moved clockwise by the spring I1 to its open circuitposition. the parts coming to rest in the positions shown in Fig. 3, inwhich the latch I9 and the parts connected to it and the arm 4I havebeen i returned or reset to their original positions. This resettingmovement is effected by means of a cam secured to the shaft I havingdiametricaliy opposite projections 4G and 41. When the shaft I turns,the projection 46 engages the electrically insulating arm 49, therebyreturning the release arm 39.to its original position, while the end ofthe arm 4I pushes downward on the link 42 to return the latch I9 to itslatching position. It will be observed that the latch link 42 isU-shaped and its lower base portion is widened and transversely arcuateso that when the arm 4I is moved upward, this base portion4 49, whilefree to move upward suiiiciently to move the latch arm I9 to a releasedposition, is still in engagement with the arm 4I whereby when the arm 4Iis reset, the link 42 is moved downward again. Thereafter when thethermostat 29 cools and moves the arm 32 upward, the arm 39 is againsecured.

It win be understood that the 'thermostat 2a and the parts operated andcontrolled by it are identical with those just described in connectionwith the thermostat 29, an electrically insulating arm 59 being providedwhich is engaged by the cam projection 41 for resetting of these partsin the event that the thermostat 29 is heated to open the switch.

The pivoted member 39 is biased to the position shown against the lowerend of the arm 39 by a spring 5I. This member 39 is movable clockwiseabout its pivot against the force of this spring to provide forresetting movement of the arm 39 in the event that the thermostat 29 hascooled and lifted the arm .32 into the path of the member 39.

With the switch in its electrically open position of Fig. 3, when theshaft I is turned counterclockwise to close the switch, the carriermember I6 is rotated with the shaft back into latching engagement withthe latch I9. A spring biased latching member 52 on the upper end o! thecarrier member moves clockwise with respect to the carriage uponengagement with the end of the latch I9 and slips by the end of thelatch I9 back `to the position shown in Fig. 4. 'I'he Darts are now inthe positions shown in Fig. 4 'with the switch closed.

While I have shown a particular embodiment of my invention, it will beunderstood, of course, that I do not wish to be limited thereto sincemany modiiications may be made, and I therefore contemplate by theappended claims to cover any such modiiications as fall within the truespirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. 'A switch comprising cooperating switch contacts at least one ofwhich is movable, a rotatably mounted operating member an operatingconnection between said operatingmember and said movable contact. acarrier member mounted for rotation, current responsive means forholding said carrier member in a predetermined angular position, springmeans independent of said operating connection for connecting saidoperating member to said carrier member for biasing said operatingmember to a closed circuit position, connections connecting said currentresponsive means in circuit with said contacts for effecting the releaseof said carrier member in response to a predetermined current in saidcontacts, and a second spring means for turning said carrier member andthereby turning said operating member through said iirst spring means toits open circuit position. A

2. A switch comprising cooperating switch contacts at least one of whichis movable, a rotatably mounted operating mem-ber connected to move saidmovable contact between open and closed circuit positions when saidoperating member is turned between two angular positions, said movablecontact being moved to its open circuit position when said operatingmember is turned in a predetermined direction, a carrier member mountedi'or rotation substantially about the axis of said operating member, ailrst spring means biasing said carrier member for rotation ing memberin an opposite direction to its closed circuit position, and connectionsconnecting said current responsive means in circuit with said contactsfor eifecting the release of said carrier member in response to apredetermined current in said contacts whereupon said carrier member isturned by said first spring means thereby to turn said operating memberin said predetermined direction to its open circuit position.

3. A switch comprising cooperating switch contacts at least one of whichis movable, a shaft connected to move said movable contact between openand closed circuit positions when the shaft is turned between twoangular positions, said movable contact being moved to its open circuitposition when said shaft is turned in a predetermined direction, acarrier member rotatably mounted on said shaft, a rst spring meansbiasing said carrier member for rotation in said predetermineddirection, releasable means for holding said carrier member in apredetermined angular position against the force of said rst springmeans, a second spring means connecting said shaft to said carriermember so that when y said carrier member is held by said latch saidsecond spring means causes said shaft to turn in an opposite directionfor movement of said movable contact to its closed circuit position, andcurrent responsive means connected in circuit with said contacts foreffecting operation of said releasable means to release said carriermember in response to a predetermined vcurrent in said contactswhereupon said carrier member is turned by said first spring thereby toturn said shaft in said predetermined direction and move said movablecontact to its open circuit position.

4. A switch comprising cooperating switch contacts at least one of whichis movable, a shaft connected to said movable contact for moving saidmovable contact between open and closed circuit positions when the shaftis turned between two angular positions, said movable contact beingmoved to its open circuit position when said shaft is turned in apredetermined direction, a carrier member rotatably mounted on saidshaft, a first spring biasing said carrier member for rotation in saidpredetermined direction, a latch for holding said carrier member in apredetermined angular position against the force of said first spring,overcenter snap spring meansconnecting said shaft to said carrier memberso that when said carrier member is held by said latch said snap springmeans causes said shaft to turn in an opposite direction for snapmovement of said movable contact to its closed circuit position, andcurrent responsive means connected in cir.. cuit with said contacts foreffecting movement of said latch to release said carrier member inresponse to a predetermined current in said contacts whereupon saidcarrier member is turned by said first spring thereby to turn said shaftin said predetermined direction and move said movable contact to itsopen circuit position.

5. A switch comprising cooperating contacts at turned in a predetermineddirection, a carrier member rotatably mounted on said shaft, a firstspring biasing said carrier member for rotation in said predetermineddirection, means for holding normally said carrier member againstrotation in each direction while said shaft is turned to operate saidmovable contact, said means including a latch for holding said carriermember against movement in at least said predetermined direction by saidfirst spring, overcenter snap spring means connecting said shaft to saidcarrier mem-perror causing said shaft to turn in each direction with asnap action for snap movement of said movable contact, cooperating stopmeans on said shaft and said carrier member for limiting the rotation ofsaid shaft in its circuit closing direction relative to said carriermember, and current responsivemeans connected in circuit with saidcontacts for effecting movement of said latch to release said carriermember for movement in said predetermined direction in response to apredetermined current in said contacts whereupon said carrier member isturned by said lrst spring thereby to turn said shaft insaidpredetermined direction and move said movable contact to its opencircuit position.

6. A switch comprising two pairs of cooperating switch contacts at leastone contact of each pair being movable, a shaft connected to saidmovable contacts for moving said contacts between open and closedcircuit positions when the shaft is turned between two positions, acarrier member rotatably mounted on said shaft, a spring biasing saidcarrier member for rotation in a predetermined direction, releasablemeans for holding said carrier member in a predetermined angularposition against the bias of said spring, snap spring means connectingsaid carrier member and said shaft so that when said carrier member isheld by said releasable means, said snap spring means causes said shaftto move between said two positions with a snap action for snap openingand closing movement of said movable contacts, and twotemperatureresponsive devices connected respectively in circuit with said pairs ofcontacts for securing normally said releasable means in a position tohold said carrier, said releasable means being released by ,movement ofeither of said temperature responsive devices in response lto apredetermined maxpositions, a carrier member rotatably mounted on saidshaft, a spring biasing said carrier member for rotation in apredetermined direction, means for holding said carrier member in apredetermined angular position including a latch for holding saidcarrier member against the bias of said spring, overcenter snap springmeans connecting said shaft to said carrier member so that when saidcarrier member is held by said latch, said snap spring means causessaid' shaft to move in an opposite direction with a snap action for snapclosing movement of said movable contacts, a spring for biasing saidlatch to a position in which said carrier member is released formovement by said first spring whereby said shaft is turned to move saidcontacts to their open circuit positions, two temperature responsivedevices connected respectively in circuit with said pairs of contactsfor securing normally said latch in a position in which said latch holdssaid carrier member, said latch being released by movement of either ofvsaid temperature responsiveI devices in responseto de predeterminedmaximum current in said switch whereupon said latch moves in accordancewith its spring bias to release said carrier member.

'8. A switch comprising two pairs of cooperating switch contacts, atleast one contact of each pair being movable, a shaft connected to saidmovable contacts for moving said movable contacts between open andclosed circuit positions when the shaft is turned between two angularpositions, said movable contacts being moved to their open circuitpositions when said shaft is turned in a predetermined direction,acarrier member rotatably mounted on said shaft, a first spring ibiasing said carrier member for rotation .in said predetermineddirection, means for holding normally saidfcarrier member againstvrotation in each direction while said shaft is turned to' operate saidmovable contacts, said means including a latch for holding said carriermember against movement in at least said predetermined direction by saidfirst spring, overcenter snap spring means connecting said shaft to saidcarrier member for causing said shaft to turn in each direction with asnap action for 'snap movement of said movable contacts, cooperatingstop means on said shaft and said carrier member for 1 mounted on theend of said arm, two temperature responsive devices connectedrespectively in circuit with said pairs of contacts for securingnormally said latch linkin a position in which said latch holds saidcarrier member, said latch link .being released by movement of either ofsaid temperature responsive devices in response to a predeterminedmaximum current in its pair of contacts for release of said carriermember and rotation of said carrier member and said shaft to their opencircuit positions.

JOSEPH W. McCLAIN.

' REFERENCES CITED The following references are of record in the -le ofthis patent:

I STATES* PATENTS Number Name Date r 1,885,246 Forman Nov. 1, 19322,315,633 May Apr. 6, 1942

